Two-Dimensional MX2 Semiconductors for Sub-5 nm Junctionless Field Effect Transistors

Peng, Bin; Zheng, Wei; Qin, Jiantao; Zhang, Wanli

doi:10.3390/ma11030430

Cited by 5 publications

(4 citation statements)

References 32 publications

(38 reference statements)

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“…To avoid these issues, the nanoelectronics community has turned to intrinsically two-dimensional (2D) material platforms. The ultrathin nature of 2D materials facilitates device downscaling and vertical stacking, , which could extend Moore’s law and enable high-density device integration for modern integrated circuits, while their atomic flatness and the absence of dangling bonds prevent scattering of carriers by surface roughness (SR), which is an advantage over ultrathin three-dimensional (3D) devices. , Despite their immunity to SR scattering, single-layer (SL) transition-metal dichalcogenides (TMDs) typically exhibit degraded carrier mobility relative to bulk due to strong Coulomb scattering from charged interfacial impurities . A viable alternative is to use few-layer (FL) TMDs, in which the bottom layers act akin to encapsulation, screening the layers above from impurities.…”

Section: Introductionmentioning

confidence: 99%

Current Rerouting Improves Heat Removal in Few-Layer WSe₂ Devices

Majee

Hemmat

Foss

et al. 2020

ACS Appl. Mater. Interfaces

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Few-layer (FL) transition-metal dichalcogenides have drawn attention for nanoelectronics applications due to their improved mobility, owing to the partial screening of charged impurities at the oxide interface. However, under realistic operating conditions, dissipation leads to self-heating, which is detrimental to electronic and thermal properties. We fabricated a series of FL-WSe2 devices and measured their I–V characteristics, while their temperatures were quantified by Raman thermometry and simulated from first principles. Our tightly integrated electrothermal study shows that Joule heating leads to a significant layer-dependent temperature rise, which affects mobility and alters the flow of current through the stack. This causes the temperatures in the top layers to increase dramatically, degrading their mobility and causing the current to reroute to the bottom of the FL stack where thermal conductance is higher. We discover that this current rerouting phenomenon improves heat removal because the current flows through layers closer to the substrate, limiting the severity of self-heating and its impact on carrier mobility. We also observe significant lateral heat removal via the contacts because of longer thermal healing length in the top layers and explore the optimum number of layers to maximize mobility in FL devices. Our study will impact future device designs and lead to further improvements in thermal management in van der Waals (vdW)-based devices.

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Section: Introductionmentioning

confidence: 99%

Current Rerouting Improves Heat Removal in Few-Layer WSe₂ Devices

Majee

Hemmat

Foss

et al. 2020

ACS Appl. Mater. Interfaces

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“…The monolayer MX 2 is modelled using a two‐band Hamiltonian at K ‐point [36]

H false(k_{x}, k_{y} false) = (][, \begin{matrix} 1em4pt \\ E_{C} & t f false(k_{x}, k_{y} false) \\ t f^{*} false(k_{x}, k_{y} false) & E_{V} \end{matrix}),

where

E_{C}

and

E_{V}

represent the band edges,

t = false(ℏ / a false) \sqrt{2 E_{normalG} / 2 m^{*}}

, and

f false(k_{x}, k_{y} false)

is given by

f false(k_{x}, k_{y} false) = \exp ()(, \frac{normali k_{y} a}{\sqrt{3}}) + 2 \exp ()(, - \frac{normali k_{y} a}{2 \sqrt{3}}) \cos ()(, \frac{k_{x} a}{2}) .

The lattice constant a , the bandgap

E_{G}

at K ‐point and the effective mass

m^{*}

are taken from [37]. The strain is not considered in this work.…”

Section: Device Structure and Simulation Approachmentioning

confidence: 99%

“…As there are six K-points in the hexagonal BZ and each K-point is shared by three adjacent units, we set n v to 2. The monolayer MX 2 is modelled using a two-band Hamiltonian at K-point [36]…”

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confidence: 99%

Physical insight and performance metrics of monolayer MX ₂ heterojunction TFETs

Alam

2020

Micro & Nano Letters

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The physics and performance of monolayer MX 2 heterojunction n TFETs are studied using a quantum simulation. The imaginary wave vector reveals that WTe 2 is the most promising source material. Results of heterojunction TFETs with WTe 2 source material and of WTe 2 homojunction TFET reveal that WTe 2-MoS 2 heterojunction TFET is the most promising candidate with a 620 μA/μm drive current for a 0.3 volt gate swing. The energy gap between the valence band of source material and the conduction band of channel material, dE cv , is the key parameter for high drive current. The WTe 2-MoS 2 heterojunction has the smallest dE cv value that results in small band bending near the heterojunction, which creates the shortest tunnel path and therefore yields the highest drive current. The WTe 2-MoS 2 TFET has an average turn-on slope of 15.6 mV/dec, an on/off current ratio of 6.2 × 10 8 , a drive current of 620 μA/μm, a transconductance of 10.98 mS/μm, a total capacitance of 0.829 fF/μm, a switching delay of 0.401 ps, and a cutoff frequency of 2.1 THz. The performance metrics closely comply with the ITRS 2026 LOP and LSTP device requirements. Its I 60 value of 11.97 μA/μm is large enough to compete with MOSFETs.

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“…Since monolayer graphene was first mechanically exfoliated from graphite in 2004 [1], its excellent physical, chemical, and mechanical properties have attracted extensive attention [2][3][4][5][6][7]. At the same time, the graphene-like two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted widespread attention due to their single-layer characteristics and their excellent mechanical properties similar to those of graphene [8][9][10][11][12][13]. Molybdenum disulfide (MoS 2 ) is a typical TMDC material, it can be obtained using mechanical stripping, a chemical approach, CVD synthesis, and other methods [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Static Bending and Forced Vibrations of Single-Layer MoS2 with Thermal Stress

Chen,

Huang,

Zhang

2024

Materials

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Single-layer molybdenum disulfide (MoS2) has been a research focus in recent years owing to its extensive potential applications. However, how to model the mechanical properties of MoS2 is an open question. In this study, we investigate the nonlinear static bending and forced vibrations of MoS2, subjected to boundary axial and thermal stresses using modified plate theory with independent in-plane and out-of-plane stiffnesses. First, two nonlinear ordinary differential equations are obtained using the Galerkin method to represent the nonlinear vibrations of the first two symmetrical modes. Second, we analyze nonlinear static bending by neglecting the inertial and damping terms of the two equations. Finally, we explore nonlinear forced vibrations using the method of multiple scales for the first- and third-order modes, and their 1:3 internal resonance. The main results are as follows: (1) The thermal stress and the axial compressive stress reduce the MoS2 stiffness significantly. (2) The bifurcation points of the load at the low-frequency primary resonance are much smaller than those at high frequency under single-mode vibrations. (3) Temperature has a more remarkable influence on the higher-order mode than the lower-order mode under the 1:3 internal resonance.

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Two-Dimensional MX2 Semiconductors for Sub-5 nm Junctionless Field Effect Transistors

Cited by 5 publications

References 32 publications

Current Rerouting Improves Heat Removal in Few-Layer WSe₂ Devices

Current Rerouting Improves Heat Removal in Few-Layer WSe₂ Devices

Physical insight and performance metrics of monolayer MX ₂ heterojunction TFETs

Nonlinear Static Bending and Forced Vibrations of Single-Layer MoS2 with Thermal Stress

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Two-Dimensional MX2 Semiconductors for Sub-5 nm Junctionless Field Effect Transistors

Cited by 5 publications

References 32 publications

Current Rerouting Improves Heat Removal in Few-Layer WSe2 Devices

Current Rerouting Improves Heat Removal in Few-Layer WSe2 Devices

Physical insight and performance metrics of monolayer MX 2 heterojunction TFETs

Nonlinear Static Bending and Forced Vibrations of Single-Layer MoS2 with Thermal Stress

Contact Info

Product

Resources

About

Current Rerouting Improves Heat Removal in Few-Layer WSe₂ Devices

Current Rerouting Improves Heat Removal in Few-Layer WSe₂ Devices

Physical insight and performance metrics of monolayer MX ₂ heterojunction TFETs